Explain the reactions of Kreb's cycle?

Krebs Cycle :

* The acetyl CoA enter into the (Mitochondrial Matrix) cyclic pathway called TCA cycle. It is
commonly called Krebs cycle.
* Krebs cycle 1st discovered by Hanskrebs.
* Krebs includes 10 steps.
Condensation : In these acetyl COA condenses with OAA and water to yield citric acid in the
presence of citrate synthetase enzyme and COA is released.
OAA+Acetyl co.A+waterm  $\stackrel{\mathrm{Citratesynthetase}}{\to }$ CA+COA
Dehydration : Citric acid looses of water molecule to yield cisaconitic acid in the presence of
enzyme aconitase.
Citric acid $\stackrel{\mathrm{Aconitase}}{\to }$ Cis - aconitric acid + H₂O
Hydration : Water molecule is added to CAA (cisaconic acid) to yield isocitric acid in the
presence of enzyme aconitase.
CAA+ H₂O $\stackrel{\mathrm{Aconitase}}{\to }$ isocitric acid
Oxidation -I : Isocitric acid undergoes oxidation in the presence of dehydrogenase enzyme to yield succinic acid.
Isocitric acid + NAD⁺ $\stackrel{\mathrm{dehydrogenase}}{\to }$ Oxalosuccinic acid+ NADH+H⁺
Decarboxylation :(OSA) oxalosuccinic acid undergoes decarboxylation in the presence
decorboxylase to form α -keto glutaric acid.

Oxalosuccinic acid $\stackrel{\mathrm{decarboxylase}}{\to }$ $\mathrm{\alpha } -$keto glutaric acid +CO₂
Oxidation- II : $\mathrm{\alpha }-$ ketoglutaric acid undergoes oxidation and decarboxylation in the presence
of dehydrogenase and condenses with CO.A form succinyl Co.A
$\mathrm{\alpha } -$ketoglutaric acid+ NAD⁺ + CO.A$\stackrel{\mathrm{dehydrogenase}}{\to }$ succinylCo.A+NADH+H+ + CO₂
Cleavage : Succinyl Co.A spilts into succinic acid and Co.A in the presence of thiokinase to form succinic acid. The energy released is utilised to from ATP from ADP and IP.
Succinyl CoA + ADP+Pi $\stackrel{\mathrm{thiokinase}}{\to } \mathrm{succinicacid}+\mathrm{ATP}+\mathrm{Co}.\mathrm{A}$
Oxidation -III : Succinic acid undergoes oxidation and forms fumaric acid in the presence of
succinic dehydrogenase.
Succinic acid + FAD $\stackrel{\mathrm{Succinic} \mathrm{dehydrogenase}}{\to }$ Fumaric acid+FADH₂
Hydration : A water molecule is added to fumaric acid the presence of fumarase to form malicacid.
Fumaric acid + H₂O $\stackrel{\mathrm{Fumarase}}{\to }$ Malic acid
Oxidation -IV : Malic acid undergoes oxidation in the presence of malic dehydrogenase to form OAA.
Mallic acid + NAD⁺ $\underset{\mathrm{dehydrogenase}}{\overset{\mathrm{Malic}}{\to }}$  OAA + NADH + H +  
* In TCA cycle every 2 molecules of acetyl Co.A undergoes oxidation and gives 2ATP,
6 NADH+H⁺, 2FADH₂ and 4 CO₂ molecules.